1. Field of the Invention
The present invention relates to high-field permanent magnets. More specifically, it relates to structures and techniques for providing non-distorting access ports in magnetic field sources.
2. Description of the Prior Art
One of the most critical problems confronting designers of high-intensity magnetic field sources has been the construction of access ports in a magnet that do not distort its working field. This problem is overcome by the present invention.
More specifically, a class of conventional magnetic field sources capable of producing high-intensity uniform fields comprise a magnetic shell and a hollow cavity in which the field is located. Examples of such magnets may be found in the following references:
Leupold, U.S. Pat. No. 4,835,506, entitled "Hollow Substantially Hemispherical Permanent Magnet High-Field Flux Source;"
Leupold, U.S. Pat. No. 4,837,542, entitled "Hollow Substantially Hemispherical Permanent Magnet High-Field Flux Source for Producing a Uniform High Field;"
Leupold, U.S. Pat. No. 4,839,059, entitled "Clad Magic Ring Wigglers;"
Leupold, U.S. Statutory Invention Registration H591, entitled "Method of Manufacturing of a Magic Ring;"
Leupold et al., "Novel High-Field Permanent-Magnet Flux Sources," IEEE Transactions on Magnetics, vol. MAG-23, No. 5, pp. 3628-3629, September 1987; and
Leupold et al., "A Catalogue of Novel Permanent-Magnet Field Sources," Paper No. W3.2, 9th International Workshop on Rare-Earth Magnets and Their Applications, pp 109-123, August 1987, Bad Soden, FRG.
Leupold et al., "Design applications of magnetic mirrors," Journal of Applied Physics, 63(8), Apr. 15, 1988, pp. 3987-3988;
Leupold et al., "Applications of yokeless flux confinement," Journal of Applied Physics. 64(10), Nov. 15, 1988, pp. 5994-5996; and
Abele et al., "A general method for flux confinement in permanent-magnet structures," Journal of Applied Physics, 64(10), Nov. 15, 1988, pp. 5988-5990.
Additionally, magnets of the type described herein may be found in my following copending U.S. patent applications that are incorporated herein by reference:
Ser. No. 654,476, filed Feb. 13, 1991, entitled "High-Power Electrical Machinery;"
Ser. No. 650,845, filed Feb. 5, 1991, entitled "High-Power Electrical Machinery with Toroidal Permanent Magnets;"
Ser. No. 709,548, filed Jun. 3, 1991, entitled "High-Field Permanent Magnet Flux Source;" and
Ser. No. 892,093, filed concurrently herewith, entitled "Field Augmentation in High-Intensity Magnetic Field Sources,"
These references show a number of different compact permanent-magnet configurations capable of producing uniform magnetic fields of unusually high intensity. In general, these magnets include a shell of magnetic material and a cavity in which the field is located. Access ports of various sizes, shapes and locations pass through the shell and communicate with the cavity. Depending on the configuration of the access ports, the field in the cavity, which is typically used as a working field, is subjected to distortions of varying degrees. When such magnets are used in applications requiring high-precision fields, these distortions are often unacceptable.
Consequently, those concerned with the development of devices requiring the use of high-precision magnets, such as Faraday rotators, extended interaction amplifiers, wigglers, traveling-wave tubes, and the like, have long recognized the need for structures and techniques that provide non-distorting access ports to a working magnetic field. The present invention fulfills this need.